1. Field of the Invention
The present invention relates to a revolution member supporting apparatus for holding and rotating a disc-shaped object (object to be rotated) such as a semiconductor wafer. The present invention also relates to a semiconductor substrate processing apparatus for forming circuit interconnects by filling a circuit pattern trench and/or hole formed in a semiconductor substrate with a plated metal film, and removing the plated metal film while leaving the metal film at the filled portion.
2. Description of the Related Art
For example, a semiconductor wafer, which has undergone a copper-plating treatment or a CMP (chemical mechanical polishing) treatment, is generally subjected to a cleaning treatment. The cleaning treatment is usually performed by supplying a cleaning liquid onto the upper surface of a semiconductor wafer around its center, while the wafer is being held horizontally and rotated by a revolution member supporting apparatus, and allowing the cleaning liquid to diffuse radially over the upper surface of the wafer by the action of centrifugal force.
It is usual with such a revolution member supporting apparatus to hold a semiconductor wafer by engaging the periphery of the wafer with a plurality of holding members.
In conventional revolution member supporting apparatuses, such holding members always engage certain fixed portions in the periphery of a semiconductor wafer when the wafer is held and rotated. Accordingly, there has been the problem that a cleaning liquid cannot reach adequately into the engaging portions, and therefore a satisfactory cleaning treatment cannot be carried out.
An attempt has been made to solve this problem by making a change of holding members during a cleaning treatment. According to this approach, for example, two pairs of holding members, each pair consisting of three members, are provided, and a semiconductor wafer is allowed to be held by each of the two pairs separately by exchanging one pair for the other according to the rotating speed of the apparatus. This approach, however, has the problem that since the number of holding members in engagement with a semiconductor wafer is relatively small, the wafer cannot be held sufficiently firmly, whereby slipping of the wafer at the engaging portions is likely to occur. This may wear the holding members and produce particles that contaminate the semiconductor wafer.
Generally, aluminum or aluminum alloys have been used as a material for forming interconnection circuits on a semiconductor substrate. The higher integrated density of semiconductor devices requires that a material having a higher electric conductivity should be used for interconnection circuits. Thus, there has been proposed a method which comprises plating a surface of a semiconductor substrate having a circuit pattern trench and/or hole formed therein to fill Cu (copper) or copper alloy into the circuit pattern trench and/or hole, and removing the Cu or copper alloy with the exception of the filled portion, thereby forming circuit interconnects.
The above method of forming circuit interconnects will be described with reference to FIGS. 1A through 1C. As shown in FIG. 1A, a conductive layer 101a is formed on a semiconductor substrate 101 on which semiconductor devices are formed, and an oxide film 102 of SiO2 is deposited on the conductive layer 101a. Then, a via hole 103 and a trench 104 for an interconnect are formed in the oxide film 2 by lithography and etching technology. Thereafter, a barrier layer 105 of TiN or the like is formed thereon, and then a seed layer 107 as an electric supply layer for electroplating is formed on the barrier layer 105.
Then, as shown in FIG. 1B, the surface of the semiconductor substrate W is coated with copper by electroplating to deposit a plated copper film 106 on the oxide film 102, thus filling the via hole 103 and the trench 104 with copper. Thereafter, the plated copper film 106 and the barrier layer 105 on the oxide film 102 are removed by chemical mechanical polishing (CMP), thus making the plated copper film 106 in the via hole 103 and the trench 104 lie flush with the oxide film 102. In this manner, an interconnect composed of the plated copper film 106 is produced as shown in FIG. 1C.
In this case, the barrier layer 105 is formed so as to cover a substantially entire surface of the oxide film 102, and the seed layer 107 is also formed so as to cover a substantially entire surface of the barrier layer 105. Thus, in some cases, as shown in FIG. 2, a copper film which is the seed layer 107 resides in a bevel (outer peripheral portion) of the semiconductor substrate W, or copper is deposited on an edge (outer peripheral portion) inwardly of the bevel of the semiconductor substrate W and remains unpolished (not shown in the drawing).
Copper can easily be diffused into the oxide film 102 in a semiconductor fabrication process such as annealing, for example, thus deteriorating the electric insulation of the oxide film and impairing the adhesiveness of the oxide film with a film to be subsequently deposited to possibly cause separation of the deposited film. It is therefore necessary to remove the remaining unnecessary copper completely from the substrate before at least film deposition. Furthermore, copper deposited on the outer peripheral portion of the substrate other than the circuit formation area is not only unnecessary, but may cause cross contamination in subsequent processes of delivering, storing and processing the semiconductor substrate. For these reasons, it is necessary that the remaining deposited copper on the peripheral portion of the substrate should be completely removed immediately after the copper film deposition process orthe CMP process. Here, the outer peripheral portion of the substrate is defined as an area including an edge and a bevel of the semiconductor substrate W, or either the edge or the bevel. The edge of the substrate means areas of the front and back surfaces of the semiconductor substrate W within about 5 mm from the outer peripheral end of the substrate, and the bevel of the substrate means an area of the outer peripheral end surface and a curved portion in a cross section of the semiconductor substrate W within 0.5 mm from the outer peripheral end of the substrate.
Recently, a so-called dry-in dry-out configuration in which a substrate is introduced in a dry state and removed in a dry state is employed in a plating apparatus for performing Cu plating of copper interconnection, and a polishing apparatus for performing chemical mechanical polishing. The apparatuses have such structure that after respective processing steps such as plating or polishing are performed, particles are removed and dried by a cleaning unit and a spin-drying unit, and the semiconductor substrate is taken out in a dry state from the respective apparatuses. In this manner, the plating apparatus and the polishing apparatus perform many common processes, which are essentially successive processes. Thus, there have been problems that the initial cost and the running cost for the apparatuses are high, installation spaces for installation of both apparatuses need to be wide, and a long processing time is required.
Currently, the driving force for semiconductor devices is changing from work stations and personal computers to digital information household electric appliances (game machines, cellular phones, digital still cameras, DVD, car navigation instruments, digital video cameras, and the like). Under these circumstances, LSI production also needs to respond to changes from general purpose LSIs used in personal computers, and the like, to system LSIs required for digital information household electric appliances.
These system LSIs are characterized by a wide variety of products, low volume production, great fluctuations in the number of products made, and a short life of product, as compared with general purpose LSIs. In order to reduce the instrument costs of digital information household electrical appliances, it is indispensable to reduce the manufacturing cost for LSIs. In semiconductor production plants as well, it is demanded to shift from the concept of large scale lines to the possession of many types of small scale lines, and minimize the production time rather than the amount of production. In order to cope with these demands, it is demanded for future semiconductor device production to respond quickly to the needs of instrument manufacturers and place semiconductor devices on the production lines as promptly as possible. Besides, since changes in demand are drastic, it is necessary that functional changes can be made flexibly, or the apparatus can be renewed.